技术领域technical field
本发明属于三相中性点不接地系统配电网线路的单相接地故障定位领域，尤其涉及一种基于扫频注入的配电网单相接地故障定位方法及系统。The invention belongs to the field of single-phase ground fault location of distribution network lines in a three-phase neutral point ungrounded system, and in particular relates to a single-phase ground fault location method and system of distribution network based on sweep frequency injection.
背景技术Background technique
国内外中压配电网广泛采用中性点不接地或经消弧线圈接地运行方式，相对于高压输电网络，中压配电网发生故障的概率高，其中单相接地故障频发。由于单相故障接地时，非故障相对地电压升高，过电压可能导致接地故障转化为相间短路故障，严重危害系统绝缘和设备安全，造成跳闸和供电中断。为了系统安全运行,需要在单相接地故障后迅速确定故障线路及故障点位置，以便进一步采取故障处理措施。The medium-voltage distribution network at home and abroad widely adopts the neutral point ungrounded or arc suppression coil grounded operation mode. Compared with the high-voltage transmission network, the medium-voltage distribution network has a high probability of failure, and single-phase ground faults occur frequently. When a single-phase fault is grounded, the non-fault phase-to-ground voltage rises, and the overvoltage may cause the ground fault to be transformed into a phase-to-phase short circuit fault, seriously endangering the system insulation and equipment safety, resulting in tripping and power supply interruption. For the safe operation of the system, it is necessary to quickly determine the fault line and the location of the fault point after a single-phase ground fault, so as to take further fault handling measures.
目前对单相接地故障定位方法主要分为主动式定位方法与被动式定位方法两类。被动式故障定位方法主要是利用故障本身所产生的电压及电流信号的特征来进行定位计算。但是，由于这种信号易受干扰，导致此种方法定位结果不够准确。主动式故障定位方法主要利用交流信号注入法，该方法主要是利用信号注入装置通过母线电压互感器向系统注入特定频率的交流电流信号，通过探测故障线路上该信号的位置分布来实现故障定位。但是，这种方法存在着注入信号受电压互感器容量限制和分布电容对注入信号的分流的影响，对于不同参数分布的配电网线路架构而言，利用该方法容易导致故障定位失败。At present, the single-phase ground fault location methods are mainly divided into two categories: active location method and passive location method. The passive fault location method mainly uses the characteristics of the voltage and current signals generated by the fault itself to perform location calculations. However, since this signal is susceptible to interference, the positioning result of this method is not accurate enough. The active fault location method mainly uses the AC signal injection method. This method mainly uses the signal injection device to inject an AC current signal of a specific frequency into the system through the bus voltage transformer, and realizes the fault location by detecting the position distribution of the signal on the fault line. However, this method has the influence of the injection signal being limited by the capacity of the voltage transformer and the shunting of the injected signal by the distributed capacitance. For the distribution network line architecture with different parameter distributions, using this method will easily lead to failure of fault location.
综上所述，进一步提高对三相中性点不接地系统配电网线路的单相接地故障的定位准确性是需要解决的问题。To sum up, it is a problem to be solved to further improve the positioning accuracy of the single-phase ground fault of the distribution network line of the three-phase neutral point ungrounded system.
发明内容Contents of the invention
本发明提供一种基于扫频注入的配电网单相接地故障定位系统和方法，以提高三相中性点不接地系统配电网线路的单相接地故障的定位准确性。The invention provides a single-phase ground fault location system and method of a distribution network based on sweep frequency injection, so as to improve the positioning accuracy of a single-phase ground fault of a three-phase neutral point ungrounded system distribution network line.
第一方面，本发明提供的基于扫频注入的配电网单相接地故障定位系统，包括若干条待定位线路，所述若干条待定位线路的输入端分别与配电网三相母线输出端连接，所述若干条待定位线路的输出端均依次电连接三相电压互感器和三个高压开关。还包括与所述三相电压互感器和三个高压开关均电连接的集中处理器，以及与所述三个高压开关均电连接的可控电源，所述可控电源的另一端接地。还包括分散设置在所述若干条待定位线路上、且均位于所述三个高压开关之后的若干故障指示器；所有的故障指示器均与所述集中处理器通信连接。In the first aspect, the distribution network single-phase ground fault location system based on sweep frequency injection provided by the present invention includes several lines to be located, and the input terminals of the several lines to be located are connected to the output terminals of the three-phase bus bars of the distribution network respectively. connected, the output terminals of the several lines to be positioned are electrically connected to three-phase voltage transformers and three high-voltage switches in sequence. It also includes a centralized processor electrically connected to the three-phase voltage transformer and the three high-voltage switches, and a controllable power supply electrically connected to the three high-voltage switches, and the other end of the controllable power supply is grounded. It also includes a number of fault indicators dispersedly arranged on the several lines to be located and located behind the three high-voltage switches; all the fault indicators are communicatively connected with the centralized processor.
优选的，上述基于扫频注入的配电网单相接地故障定位系统中，所述可控电源为级联H桥。Preferably, in the single-phase-to-ground fault location system of distribution network based on sweep frequency injection, the controllable power supply is a cascaded H-bridge.
优选的，上述基于扫频注入的配电网单相接地故障定位系统中，靠近所述可控电源的接地端处设置有与所述集中处理器电连接的返回电流检测装置。Preferably, in the single-phase ground fault location system of distribution network based on frequency sweep injection, a return current detection device electrically connected to the centralized processor is provided near the ground terminal of the controllable power supply.
优选的，上述基于扫频注入的配电网单相接地故障定位系统中，所述集中处理器包括依次电连接的三相母线对地实时电压接收模块、单相故障判断模块、可控电源接入故障相控制模块、扫频注入命令发送模块、实时特征电流接收模块和单相接地故障定位模块；其中，所述三相母线对地实时电压接收模块与所述三相电压互感器电连接，所述可控电源接入故障相控制模块和所述高压开关电连接，所述扫频注入命令发送模块与所述可控电源电连接，所述实时特征电流接收模块与所述故障指示器通信连接。Preferably, in the above-mentioned single-phase ground fault location system based on frequency sweep injection, the centralized processor includes a three-phase busbar-to-ground real-time voltage receiving module, a single-phase fault judgment module, a controllable power connection input fault phase control module, frequency sweep injection command sending module, real-time characteristic current receiving module and single-phase ground fault location module; wherein, the three-phase bus-to-ground real-time voltage receiving module is electrically connected to the three-phase voltage transformer, The controllable power supply access fault phase control module is electrically connected to the high voltage switch, the frequency sweep injection command sending module is electrically connected to the controllable power supply, and the real-time characteristic current receiving module communicates with the fault indicator connect.
优选的，上述基于扫频注入的配电网单相接地故障定位系统中，所述故障指示器包括特征电流发送模块，所述特征电流发送模块与所述实时特征电流接收模块通信连接。Preferably, in the single-phase-to-earth fault location system of distribution network based on frequency sweep injection, the fault indicator includes a characteristic current sending module, and the characteristic current sending module is communicatively connected with the real-time characteristic current receiving module.
结合第一方面，本发明的第二方面提供了一种基于扫频注入定位配电网单相接地故障的方法，应用于集中处理器中，该方法包括，In combination with the first aspect, the second aspect of the present invention provides a method for locating a single-phase-to-ground fault in a distribution network based on frequency sweep injection, which is applied to a centralized processor, and the method includes:
接收三相电压互感器发送的配电网三相母线对地实时电压；Receive the real-time voltage of the three-phase busbar of the distribution network to the ground sent by the three-phase voltage transformer;
根据所述述三相母线对地电压判断是否出现单相故障，如果是，继续判断故障相；Judging whether a single-phase fault occurs according to the voltage of the three-phase bus bar to ground, if so, continue to judge the fault phase;
控制与所述故障相对应的高压开关闭合，使得可控电源接入所述故障相；controlling the high-voltage switch corresponding to the fault to close, so that the controllable power supply is connected to the fault phase;
发送故障点定位命令至所述可控电源，以使其利用扫频法向故障相注入频率和幅值可调的电压或电流，且使得在所述故障相故障点的上游的线路上产生所述特征电流；Sending a fault point location command to the controllable power supply, so that it injects a voltage or current with adjustable frequency and amplitude into the fault phase by using the frequency sweep method, and causes all faults to be generated on the upstream line of the fault point of the fault phase The characteristic current;
接收故障相上每个故障指示器发送的实时特征电流组，所述每组实时特征电流均包括与三相母线同一位置对应的三个特征电流，所述实时特征电流均携带有对应的故障指示测器的位置信息；Receive the real-time characteristic current group sent by each fault indicator on the fault phase, each group of real-time characteristic currents includes three characteristic currents corresponding to the same position of the three-phase bus, and the real-time characteristic currents all carry corresponding fault indications location information of the detector;
确定三个特征电流的幅值不相等的实时特征电流组所对应的故障指示器中，距离三相母线的输出端最远的故障指示器之后的位置为故障位置。Among the fault indicators corresponding to the real-time characteristic current groups whose amplitudes of the three characteristic currents are not equal, the position behind the fault indicator farthest from the output end of the three-phase bus is the fault position.
优选的，还包括实时检测可控电源的接地电流。Preferably, it also includes real-time detection of the ground current of the controllable power supply.
优选的，所诉发送故障点定位命令至所述可控电源，以使其利用扫频法向故障相注入频率和幅值可调的电压或电流，且使得在所述故障相故障点的上游的线路上产生所述特征电流具体是指：Preferably, the said fault point location command is sent to the controllable power supply, so that it injects a voltage or current with adjustable frequency and amplitude into the fault phase by using the frequency sweep method, and makes the upstream of the fault point of the fault phase The characteristic current generated on the line specifically refers to:
确定所述注入频率的初始频率值、频率步长和终止频率值；determining an initial frequency value, a frequency step size, and a stop frequency value of the injection frequency;
确定初始电流/电压幅值、电流/电压步长和终止电流/电压幅值；Determine the initial current/voltage amplitude, current/voltage step size and end current/voltage amplitude;
可控电源按频率步长，从初始频率值改变输出频率至终止频率值，完成一次扫频，按电流/电压步长，从初始电流/电压幅值改变输出电流/电压幅值至终止电流/电压幅值，重复进行扫频；直到集中处理器确定出故障点位置或者达到终止电流/电压幅值为止结束扫频注入过程，以使得在所述故障相故障点的上游线路上产生所述特征电流。The controllable power supply changes the output frequency from the initial frequency value to the stop frequency value according to the frequency step, completes a frequency sweep, and changes the output current/voltage amplitude from the initial current/voltage amplitude to the end current/voltage step according to the current/voltage step. Voltage amplitude, repeat frequency sweep; end the sweep frequency injection process until the centralized processor determines the location of the fault point or reaches the termination current/voltage amplitude, so that the characteristic is generated on the upstream line of the fault point of the fault phase current.
优选的，所述注入频率fcom的满足以下范围区间：Preferably, the injection frequency fcom satisfies the following range:
其中，R为故障点接地电阻值，C0为正常运行系统单相线路对地电容值，ω为电源角频率，为接地故障相上的电压幅值，为中性点对地电压幅值；所述注入电流幅值范围小于或等于所述接地电流的二十分之一。Among them, R is the ground resistance value of the fault point, C0 is the capacitance value of the single-phase line of the normal operation system to the ground, ω is the angular frequency of the power supply, is the voltage amplitude on the ground fault phase, is the neutral point-to-ground voltage amplitude; the range of the injected current amplitude is less than or equal to one-twentieth of the ground current.
优选的，所述注入电流为直流或交流电流。Preferably, the injection current is direct current or alternating current.
本发明采用主动式定位方式定位单相接地故障。通过可控电源为三相母线中注入电流，可控电源注入电流，具有频率广，幅值可调，而且可以实现电压或电流输出的优点。注入过程利用扫频法，注入电流可以根据不同的电网架构参数设定范围，并从中选取最优注入特征电流，依据故障指示器回传的三相母线各相中针对最优注入特征电流产生的实时特征电流值精确定位出故障区域，相比现有的定位方式，准确率更高。The invention adopts an active positioning method to locate single-phase grounding faults. The controllable power supply injects current into the three-phase bus, and the controllable power supply injects current, which has the advantages of wide frequency, adjustable amplitude, and can realize voltage or current output. The injection process uses the frequency sweep method. The range of injection current can be set according to different grid structure parameters, and the optimal injection characteristic current can be selected from it. According to the optimal injection characteristic current generated in each phase of the three-phase bus returned by the fault indicator The real-time characteristic current value accurately locates the fault area, which is more accurate than the existing positioning methods.
附图说明Description of drawings
图1为本发明实施例提供的基于扫频注入的配电网单相接地故障定位系统的结构示意图；Fig. 1 is a schematic structural diagram of a distribution network single-phase ground fault location system based on sweep frequency injection provided by an embodiment of the present invention;
图2为图1中特征电压注入电路的结构示意图；Fig. 2 is a schematic structural diagram of the characteristic voltage injection circuit in Fig. 1;
图3为图1中集中处理器的结构示意图；Fig. 3 is the structural representation of centralized processor in Fig. 1;
其中1-集中处理器，101-三相母线对地实时电压接收模块，102-单相故障判断模块，103-可控电源接入故障相控制模块，104-扫频注入命令发送模块，105-实时特征电流接收模块，106-单相接地故障定位模块，2-三相电压互感器，3-高压开关，4-可控电源，5-故障指示器，501-特征电流发送模块，6-返回电流检测装置。Among them, 1-centralized processor, 101-three-phase bus-to-ground real-time voltage receiving module, 102-single-phase fault judgment module, 103-controllable power supply access fault phase control module, 104-sweep frequency injection command sending module, 105- Real-time characteristic current receiving module, 106-single-phase ground fault location module, 2-three-phase voltage transformer, 3-high voltage switch, 4-controllable power supply, 5-fault indicator, 501-characteristic current sending module, 6-return Current detection device.
具体实施方式Detailed ways
本发明提供一种基于扫频注入的配电网单相接地故障定位系统和方法，以提高三相中性点不接地系统配电网线路的单相接地故障的定位准确性。以下以实施例的方式进行说明。The invention provides a single-phase ground fault location system and method of a distribution network based on sweep frequency injection, so as to improve the positioning accuracy of a single-phase ground fault of a three-phase neutral point ungrounded system distribution network line. The following will be described in the form of an embodiment.
本发明提供的基于扫频注入的配电网单相接地故障定位系统，包括若干条待定位线路，所述若干条待定位线路的输入端分别与配电网三相母线输出端连接。所述若干条待定位线路的输出端均依次电连接三相电压互感器和三个高压开关。还包括与所述三相电压互感器和三个高压开关均电连接的集中处理器，以及与所述三个高压开关均电连接的可控电源，所述可控电源的另一端接地。还包括分散设置在所述若干条待定位线路上、且均位于所述三个高压开关之后的若干故障指示器；所有的故障指示器均与所述集中处理器通信连接。The distribution network single-phase ground fault location system based on frequency sweep injection provided by the present invention includes several lines to be located, and the input ends of the several lines to be located are respectively connected to the output ends of the three-phase bus bars of the distribution network. The output ends of the plurality of lines to be positioned are electrically connected to three-phase voltage transformers and three high-voltage switches in sequence. It also includes a centralized processor electrically connected to the three-phase voltage transformer and the three high-voltage switches, and a controllable power supply electrically connected to the three high-voltage switches, and the other end of the controllable power supply is grounded. It also includes a number of fault indicators dispersedly arranged on the several lines to be located and located behind the three high-voltage switches; all the fault indicators are communicatively connected with the centralized processor.
本发明提供的定位系统，三相母线连接的待定位线路可以为多条，本发明对线路条数不做限定。实施中，只需将母线分成若干分支，分别将各条待定位线路接入此若干分支，使得所有的待定位线路均接入三相母线中。请参考图1，该图示出了本发明实施例提供的基于扫频注入的配电网单相接地故障定位系统的结构。该实施例以三相母线的输出端连接三条待定位线路为例进行说明。如图所示，该定位系统包括三条待定位线路，这三条待定位线路的输入端分别与配电网三相母线输出端连接，这三条待定位线路的输出端均依次电连接三相电压互感器2和三个高压开关3。三个高压开关为K1、K2、和K3，分别与三相母线中的A相、B相和C相连接。还包括与三相电压互感器2和三个高压开关3均电连接的集中处理器1，以及与所述三个高压开关3均电连接的可控电源4，所述可控电源4的另一端接地。In the positioning system provided by the present invention, there may be multiple lines to be positioned connected to the three-phase bus bars, and the present invention does not limit the number of lines. During implementation, it is only necessary to divide the busbar into several branches, and connect each line to be located to these branches, so that all lines to be located are connected to the three-phase busbar. Please refer to FIG. 1 , which shows the structure of a single-phase-to-ground fault location system for a power distribution network based on frequency sweep injection provided by an embodiment of the present invention. This embodiment is described by taking the output end of a three-phase bus connected to three lines to be located as an example. As shown in the figure, the positioning system includes three lines to be located. The input terminals of the three lines to be located are respectively connected to the output terminals of the three-phase bus bars of the distribution network. The output terminals of the three lines to be located are all connected to the three-phase voltage mutual inductance device 2 and three high voltage switches 3. The three high-voltage switches are K1 , K2 , and K3 , which are respectively connected to phase A, phase B, and phase C of the three-phase bus. It also includes a centralized processor 1 that is electrically connected to the three-phase voltage transformer 2 and three high-voltage switches 3, and a controllable power supply 4 that is electrically connected to the three high-voltage switches 3, and the other of the controllable power supply 4 One end is grounded.
还包括分散设置在所述若干条待定位线路上、且均位于所述三个高压开关3之后的若干故障指示器5；所有的故障指示器均与所述集中处理器(1)通信连接。如图1所示，故障指示器标记为A至F。所有的故障指示器均与所述集中处理器1通信连接。故障指示器就是故障指示器，具备电流检测、故障报警等功能。可以识别注入的特定频率电流，读取特征电流幅值信息。A至F均包括连接在三相母线同一位置对应的三个故障指示器。待定位线路1中接入的是A和D，待定位线路2中接入的是B和F，待定位线路3中接入的是C和E。It also includes a number of fault indicators 5 dispersedly arranged on the several lines to be located and located behind the three high-voltage switches 3; all the fault indicators are communicatively connected with the centralized processor (1). The fault indicators are labeled A through F as shown in Figure 1. All fault indicators are communicatively connected with the centralized processor 1 . The fault indicator is a fault indicator, which has functions such as current detection and fault alarm. The specific frequency of the injected current can be identified, and the characteristic current amplitude information can be read. A to F all include three corresponding fault indicators connected to the same position of the three-phase bus. A and D are connected to line 1 to be located, B and F are connected to line 2 to be located, and C and E are connected to line 3 to be located.
该系统的工作过程分为三个阶段。第一个阶段为判断是否出现单相故障；第二个阶段为利用扫频法向故障相注入特征电流，注入开始前调整注入特征电流为最优注入特征电流，第三为当注入电流为最优注入特征电流时，定位故障相的单相接地位置。以下按照这三个工作阶段的顺序说明该系统的工作过程。The working process of the system is divided into three stages. The first stage is to judge whether there is a single-phase fault; the second stage is to use the frequency sweep method to inject the characteristic current into the fault phase. Before the injection, the injection characteristic current is adjusted to the optimal injection characteristic current; Locate the single-phase grounding position of the faulty phase when the characteristic current is optimally injected. The following describes the working process of the system according to the order of the three working stages.
在第一阶段中三相电压互感器4检测配电网三相母线对地实时电压，并将此实时对地电压发送至集中处理器。结合图1，得到了三个实时对地电压UA、UB和UC，当无单相接地故障时，UA、UB和UC应该相等或近似相等，而如果UA、UB或UC中出现了其中某项突然变低，其余两相升高但小于线电压，则判断出现单相接地故障，且UA、UB或UC中实时电压降低的相即为故障相，需要立刻对此故障定位。结合图1，假定单相接地故障点为Ig，故障相为C相。定位前，集中处理器1控制与C相对应的高压开关K3闭合，使得可控电源4接入所述C相。那么，闭合C相后就使得故障指示器C和E与可控电源4接通。In the first stage, the three-phase voltage transformer 4 detects the real-time ground voltage of the three-phase busbar of the distribution network, and sends the real-time ground voltage to the centralized processor. Combined with Figure 1, three real-time ground voltages UA , UB and UC are obtained. When there is no single-phase ground fault, UA , UB and UC should be equal or approximately equal, and if UA , UB Or if one of the items in UC suddenly becomes low, and the other two phases rise but are lower than the line voltage, it is judged that a single-phase ground fault occurs, and the phase whose real-time voltage drops in UA , UB or UC is the fault phase. The fault needs to be located immediately. Combined with Figure 1, it is assumed that the single-phase ground fault point is Ig , and the fault phase is C phase. Before positioning, the centralized processor 1 controls the high-voltage switch K3 corresponding to C to close, so that the controllable power supply 4 is connected to the C phase. Then, after closing phase C, the fault indicators C and E are connected to the controllable power supply 4 .
本方法采用的特征电压注入电路如图2所示，可控电源4采用级联H桥拓扑，每个级联H桥的直流侧都采用直流电源进行供电，通过PWM调制技术，级联H桥可以在C相母线和地之间注入一定频率和幅值的特征电压。所述可控电源可以为级联H桥。利用级联H桥注入电流是因为以下两个原因：第一，级联H桥是直挂设备的常用结构形式，可以满足直接挂网时的输出电压要求，对于不同架构的电网可以匹配不同的级联H桥。第二，级联H桥在输出特定频率电流时，谐波更少，去掉变压器耦合环节使得可注入的电流幅值增大，有利于定位的准确性。The characteristic voltage injection circuit used in this method is shown in Figure 2. The controllable power supply 4 adopts a cascaded H-bridge topology, and the DC side of each cascaded H-bridge is powered by a DC power supply. Through PWM modulation technology, the cascaded H-bridge A characteristic voltage of a certain frequency and amplitude can be injected between the C-phase bus and the ground. The controllable power supply may be a cascaded H-bridge. The cascaded H-bridge is used to inject current for the following two reasons: First, the cascaded H-bridge is a common structural form of direct-connected equipment, which can meet the output voltage requirements when directly connected to the grid, and can match different power grids with different architectures. Cascaded H-bridges. Second, when the cascaded H-bridge outputs a specific frequency current, there are fewer harmonics, and the removal of the transformer coupling link increases the amplitude of the injectable current, which is conducive to the accuracy of positioning.
级联H桥的可控电源的注入电流可以为直流注入方式也可以是交流注入方式，没有规定可以依据具体情况选择两种注入方式组合使用。The injection current of the controllable power supply of the cascaded H-bridge can be DC injection or AC injection, and there is no regulation that the combination of the two injection methods can be selected according to the specific situation.
在第二阶段中，集中处理器1发送故障点定位命令至所述可控电源4，以使其利用扫频法向C相注入频率和幅值可调的电压或电流，且使得在C相故障点Ig的上游的线路上产生特征电流。当C相母线处注入一定量的特征对地电压后，C相线路中会产生相同频率的特征电流，此特征电流会从线路对地电容C1和接地点Ig流过，并流回级联H桥。C线路上的C和E故障指示器会测得特征电流幅值信息，且这些实时特征电流均携带有对应的位置信息，此位置信息是指地理位置信息。通过无线通信将实时特征电流传回集中处理系统，从而可以判定接地点的具体区间。靠近所述可控电源的接地端处设置有与所述集中处理器电连接的返回电流检测装置，用于实时检测从可控电源流出的注入电流，经过故障相产生了特征电流，并流回级联H桥时的回流电流值。此回流电流值与故障指示器回传至集中处理器的实时特征电流值相结合，可以作为反馈并调整可控电源实时注入电流的依据。通过此反馈可以将可控电源你的注入电流调整至和电网架构参数最匹配的最优注入特征电流。调整的过程利用扫频注入法实现。In the second stage, the centralized processor 1 sends a fault point location command to the controllable power supply 4, so that it injects a voltage or current with adjustable frequency and amplitude into the C phase by using the frequency sweep method, and makes the phase C A characteristic current occurs on the line upstream of the fault pointIg . When a certain amount of characteristic voltage to ground is injected into the C-phase bus, a characteristic current of the same frequency will be generated in the C-phase line, and this characteristic current will flow through the line-to-ground capacitanceC1 and the ground pointIg , and flow back to the stage United H bridge. The C and E fault indicators on the C line will measure the characteristic current amplitude information, and these real-time characteristic currents carry corresponding location information, which refers to geographic location information. The real-time characteristic current is transmitted back to the centralized processing system through wireless communication, so that the specific interval of the grounding point can be determined. Close to the ground terminal of the controllable power supply, a return current detection device electrically connected to the centralized processor is provided for real-time detection of the injection current flowing out from the controllable power supply, and a characteristic current is generated through the fault phase and flows back to the controllable power supply. Return current value when cascading H bridges. This return current value is combined with the real-time characteristic current value sent back from the fault indicator to the centralized processor, which can be used as a basis for feedback and adjustment of the real-time injection current of the controllable power supply. Through this feedback, the injection current of the controllable power supply can be adjusted to the optimal injection characteristic current that best matches the grid architecture parameters. The adjustment process is realized by frequency sweep injection method.
在第二阶段中，扫频注入法具体是指：在确定所述注入频率的初始频率值、频率步长和终止频率值，确定初始电流/电压幅值、电流/电压步长和终止电流/电压幅值后，可控电源按频率步长，从初始频率值改变输出频率至终止频率值，完成一次扫频，按电流/电压步长，从初始电流/电压幅值改变输出电流/电压幅值至终止电流/电压幅值，重复进行扫频；直到集中处理器确定出故障点位置或者达到终止电流/电压幅值为止结束扫频注入过程，以使得在所述故障相故障点的上游线路上产生所述特征电流。In the second stage, the sweep frequency injection method specifically refers to: after determining the initial frequency value, frequency step size and stop frequency value of the injection frequency, determine the initial current/voltage amplitude, current/voltage step size and stop current/ After the voltage amplitude, the controllable power supply changes the output frequency from the initial frequency value to the stop frequency value according to the frequency step, completes a frequency sweep, and changes the output current/voltage amplitude from the initial current/voltage amplitude according to the current/voltage step value to the termination current/voltage amplitude, and repeat the frequency sweep; until the centralized processor determines the location of the fault point or reaches the termination current/voltage amplitude, the frequency sweep injection process is ended, so that the upstream line of the fault point in the fault phase produces the characteristic current.
其中，最优注入特征电流的选择具体操作为：首先根据中性点对地电压UA、UB和故障相电压UC计算接地电阻值。为了减少故障相线路分布电容对线路特征电流的分流影响，根据接地电阻与分布电容的阻抗之间的关系可以得到注入电流频率的范围。再次，通过图1中所示靠近可控电源4的接地端处设置的返回电流检测装置6实时检测可控电源的接地电流。考虑注入电流对系统的影响，根据故障指示器检测精度和接地电流大小，确定注入电流幅值范围。试验得出，所述注入电流幅值范围小于或等于所述接地电流的二十分之一时电流对系统的影响较小且同时易于检测。接地电流发送至集中处理器1，集中处理器根据接地电流控制可控电源的输出电流的幅值小于或等于所述接地电流的二十分之一。Among them, the specific operation of selecting the optimal injection characteristic current is as follows: first, calculate the grounding resistance value according to the neutral point- to-ground voltage UA , UB and the fault phase voltage UC . In order to reduce the shunting effect of the distributed capacitance of the faulty phase line on the characteristic current of the line, the frequency range of the injected current can be obtained according to the relationship between the grounding resistance and the impedance of the distributed capacitance. Thirdly, the ground current of the controllable power supply is detected in real time by the return current detection device 6 provided near the ground terminal of the controllable power supply 4 shown in FIG. 1 . Considering the impact of the injected current on the system, the amplitude range of the injected current is determined according to the detection accuracy of the fault indicator and the magnitude of the grounding current. Experiments have shown that when the amplitude range of the injection current is less than or equal to one-twentieth of the ground current, the impact of the current on the system is small and at the same time it is easy to detect. The ground current is sent to the centralized processor 1, and the centralized processor controls the amplitude of the output current of the controllable power supply according to the ground current to be less than or equal to one-twentieth of the ground current.
注入频率fcom的满足以下范围区间：The injection frequency fcom satisfies the following range intervals:
其中，R为故障点接地电阻值，C0为正常运行系统单相线路对地电容值，ω为电源角频率，为接地故障相上的电压幅值，为中性点对地电压幅值。对于同一个电网电路，和为常量。Among them, R is the ground resistance value of the fault point, C0 is the capacitance value of the single-phase line to ground in the normal operation system, ω is the angular frequency of the power supply, is the voltage amplitude on the ground fault phase, is the voltage amplitude of the neutral point to ground. For the same grid circuit, and is a constant.
在确定了电流注入的频率范围和幅值范围后，确定可控电源输出电压注入或电流注入。如果是电流注入，初始电流选定为最小值，扫频过程中，频率从计算的可选范围的最大值开始，按频率步长逐渐调节到0Hz完成一次扫频，按照电流步长增大注入电流，直到集中处理系统能接收到故障指示器发送的信号为止。如果是电压注入，初始电压从0v开始，扫频过程中，频率从计算的可选范围的最大值开始，按频率步长逐渐调节到0Hz完成一次扫频，按照电压步长增大注入电压，直到集中处理系统能接收到故障指示器发送的信号为止。After determining the frequency range and amplitude range of the current injection, determine the output voltage injection or current injection of the controllable power supply. If it is current injection, the initial current is selected as the minimum value. During the frequency sweep, the frequency starts from the maximum value of the calculated optional range, and is gradually adjusted to 0Hz according to the frequency step to complete a frequency sweep, and the injection is increased according to the current step. Current until the centralized processing system can receive the signal sent by the fault indicator. If it is voltage injection, the initial voltage starts from 0v. During the frequency sweep, the frequency starts from the maximum value of the calculated optional range, and is gradually adjusted to 0Hz according to the frequency step to complete a frequency sweep. Increase the injection voltage according to the voltage step. Until the centralized processing system can receive the signal sent by the fault indicator.
下面以具体数值举例说明扫频注入法的过程。首先获取配电网的对地电容C0、接地电阻R。初始频率设置为计算的注入特征频率的最大值，以频率步长5Hz依次减小，终止频率0Hz。电流注入下，为便于故障指示器对特征电流的检测，初始电流幅值设置为50mA，电流以步长10mA增大，终止电流幅值按照接地电流的大小设置为5％的接地电流(一般在20A～30A大小)。电压注入下，初始电压幅值设置为0V，电压步长设置为30V，终止电压幅值根据装置的直流电压而决定，设置为直流电压的5％，这样保证始终在装置可提供的容量范围内。按照上述参数设定，从初始频率值改变输出频率至终止频率值，完成一次扫频，按电流/电压步长，从初始电流/电压幅值改变输出电流/电压幅值至终止电流/电压幅值，重复进行扫频；直到集中处理器确定出故障点位置或者达到终止电流/电压幅值为止结束扫频注入过程。The process of the frequency-sweeping injection method is illustrated below with specific numerical examples. Firstly, the ground capacitance C0 and ground resistance R of the distribution network are obtained. The initial frequency was set to the maximum value of the calculated injection characteristic frequency, which was successively decreased with a frequency step of 5 Hz, and the stop frequency was 0 Hz. Under current injection, in order to facilitate the detection of the characteristic current by the fault indicator, the initial current amplitude is set to 50mA, the current increases with a step size of 10mA, and the termination current amplitude is set to 5% of the ground current according to the magnitude of the ground current (generally at 20A～30A size). Under voltage injection, the initial voltage amplitude is set to 0V, the voltage step is set to 30V, and the final voltage amplitude is determined according to the DC voltage of the device, which is set to 5% of the DC voltage, so as to ensure that it is always within the capacity that the device can provide . According to the above parameter settings, change the output frequency from the initial frequency value to the end frequency value, complete a frequency sweep, and change the output current/voltage amplitude from the initial current/voltage amplitude to the end current/voltage amplitude according to the current/voltage step. value, repeat the frequency sweep; the frequency sweep injection process ends until the centralized processor determines the location of the fault point or reaches the termination current/voltage amplitude.
在第三阶段中，经过上述过程，确定了最优注入特征电流后，针对此最优特征电流值精确定位出故障区域。具体定位过程为：确定三个特征电流的幅值不相等的实时特征电流组所对应的故障指示器中，距离三相母线的输出端最远的故障指示器之后的位置为故障位置。结合图1，具体过程为：C和E故障指示器中安在同一位置的三个故障指示器将检测到的特征电流幅值传回至集中处理器。当发生单相接地故障时，在故障点之前的同一位置的故障指示器中三个特征电流中会出现一个特征量交其他两个电流明显增加的情况，而故障点之后的位置的故障指示器的三个特征电流的电流值会基本一致。因此，可以通过在集中处理器中对所有回传的特征电进行比较，判断同一位置中具有较大特征电流量的为故障相，且根据特征电流中携带的位置信息，确定三个特征电流的幅值不相等的实时特征电流组所对应的故障指示器中，距离三相母线的输出端最远的故障指示器之后的位置为故障位置。结合图1，故障相为C相，故障位置为Ig,当向C相注入了特征电流，C故障指示器所检测到的特征电流量，而E故障指示器所未检测到特征电流量，集中处理系统则可以根据传回信号，可以确定单相接地故障点位于C故障指示器和E故障指示器之间的配电线路上。In the third stage, after the above-mentioned process, after the optimal injection characteristic current is determined, the fault area is accurately located according to the optimal characteristic current value. The specific positioning process is as follows: among the fault indicators corresponding to the real-time characteristic current groups whose amplitudes of the three characteristic currents are not equal, the position after the fault indicator farthest from the output end of the three-phase bus is determined as the fault location. Combining with Fig. 1, the specific process is as follows: the three fault indicators installed in the same position among the C and E fault indicators send the detected characteristic current amplitude back to the centralized processor. When a single-phase ground fault occurs, one of the three characteristic currents in the fault indicator at the same position before the fault point will increase significantly, and the other two currents will increase significantly, while the fault indicator at the position after the fault point The current values of the three characteristic currents will be basically the same. Therefore, by comparing all the returned characteristic currents in the centralized processor, it can be judged that the phase with the larger characteristic current in the same position is the fault phase, and according to the position information carried in the characteristic current, the three characteristic currents can be determined. Among the fault indicators corresponding to the real-time characteristic current groups with unequal amplitudes, the position behind the fault indicator farthest from the output end of the three-phase bus is the fault position. Combined with Figure 1, the fault phase is phase C, and the fault location is Ig. When the characteristic current is injected into phase C, the characteristic current detected by the C fault indicator, and the characteristic current not detected by the E fault indicator, concentrate The processing system can determine that the single-phase ground fault point is located on the distribution line between the C fault indicator and the E fault indicator according to the returned signal.
虽然图1中故障相上的故障指示器只示出了C和E，且故障点Ig之前的故障指示器只示出了C。但是图1只是示例性的，如果配电网长度较长且故障率较高，可以提高故障指示器的布置密度，例如，在图1中在C和E之间依次布置五个故障指示器C1-C5，为了能够更准确找到接地点Ig究竟位于C1-C5的精确位置，可以通过注入多个不同频率和幅值电流信号。集中处理器得到多次C1-C5的传回的三组实时特征电流。一个频率和幅值的注入电流，对应一次传回的实时特征电流。例如，第一次回传后，在C1-C5中三个特征电流中，均出现一个特征量交其他两个电流明显增加的情况，第N次回传后，在C1-C5中三个特征电流中，只有C1-C3出现一个特征量交其他两个电流明显增加的情况，C4-C5未出现这种情况，可见根据多次回传信息可以更准确的确定单相接地故障点，直到锁定故障点Ig精确位置。其中，不同频率的特征电流的频率范围满足上述fcom的范围。Although the fault indicator on the fault phase in Fig. 1 only shows C and E, and the faultindicator before the fault point Ig only shows C. But Figure 1 is just an example, if the distribution network is long and the failure rate is high, the layout density of fault indicators can be increased, for example, five fault indicators C are arranged in sequence between C and E in Figure 11 -C5 , in order to find out exactly where the grounding point Ig is located in C1 -C5 more accurately, multiple current signals with different frequencies and amplitudes can be injected. The centralized processor obtains three groups of real-time characteristic currents returned by C1 -C5 multiple times. An injected current with a frequency and amplitude corresponds to a real-time characteristic current transmitted back once. For example, after the first return, among the three characteristic currents in C1 -C5 , one characteristic quantity and the other two currents increase significantly. After the Nth return, in C1 -C5 Among the three characteristic currents, only C1 -C3 has a characteristic quantity and the other two currents increase significantly, but C4 -C5 does not. It can be seen that the single-phase can be determined more accurately based on the information returned multiple times Ground the fault point until the precise location of the fault point Ig is locked. Wherein, the frequency ranges of the characteristic currents of different frequencies satisfy the range of fcom mentioned above.
综上所述，本发明采用主动式定位方式定位单相接地故障。通过可控电源为三相母线中注入电流，可控电源注入电流，具有频率广，幅值可调，而且可以实现电压或电流输出的优点。注入过程利用扫频法，注入电流可以根据不同的电网架构参数设定范围，并从中选取最优注入特征电流，依据故障指示器回传的三相母线各相中针对最优注入特征电流产生的实时特征电流值精确定位出故障区域，相比现有的定位方式，准确率更高。To sum up, the present invention uses an active positioning method to locate single-phase ground faults. The controllable power supply injects current into the three-phase bus, and the controllable power supply injects current, which has the advantages of wide frequency, adjustable amplitude, and can realize voltage or current output. The injection process uses the frequency sweep method. The range of injection current can be set according to different grid structure parameters, and the optimal injection characteristic current can be selected from it. According to the optimal injection characteristic current generated in each phase of the three-phase bus returned by the fault indicator The real-time characteristic current value accurately locates the fault area, which is more accurate than the existing positioning methods.
为了实现上述的三个工作阶段，请参考图3，该图示出了集中处理器的结构。所述集中处理器包括依次电连接的三相母线对地实时电压接收模块101、单相故障判断模块102、可控电源接入故障相控制模块103、扫频注入命令发送模块104、实时特征电流接收模块105和单相接地故障定位模块106；其中，所述三相母线对地实时电压接收模块101与所述三相电压互感器2电连接，所述可控电源接入故障相控制模块103和所述高压开关3电连接，所述扫频注入命令发送模块104与所述可控电源4电连接，所述实时特征电流接收模块105与所述故障指示器通信501连接。通信连接方式可以优选为无线通信方式。所述故障指示器5包括特征电流发送模块，所述特征电流发送模块501与所述实时特征电流接收模块105通信连接。集中处理器的工作过程为：三相母线对地实时电压接收模块101接收三相电压互感器2发送的实时三相对地电压，单相故障判断模块102根据所述述三相母线对地电压判断是否出现单相故障，如果是，继续判断故障相。当判断出故障相后，可控电源接入故障相控制模块103控制与所述故障相对应的高压开关闭合，使得可控电源接入所述故障相。扫频注入命令发送模块104发送故障点定位命令至所述可控电源，以使其利用扫频法向故障相注入频率和幅值可调的电压或电流，且使得在所述故障相故障点的上游的线路上产生所述特征电流。实时特征电流接收模块105接收故障相上每个故障指示器中故障指示器通信501发送的实时特征电流组。单相接地故障定位模块106确定三个特征电流的幅值不相等的实时特征电流组所对应的故障指示器中，距离三相母线的输出端最远的故障指示器之后的位置为故障位置。详细的过程可以参考上述关于基于扫频注入的配电网单相接地故障定位系统的三个阶段的工作过程的介绍，此不赘述。In order to realize the above three working stages, please refer to FIG. 3 , which shows the structure of the centralized processor. The centralized processor includes a three-phase bus-to-ground real-time voltage receiving module 101, a single-phase fault judgment module 102, a controllable power supply access fault phase control module 103, a frequency sweep injection command sending module 104, a real-time characteristic current A receiving module 105 and a single-phase ground fault location module 106; wherein, the three-phase bus-to-ground real-time voltage receiving module 101 is electrically connected to the three-phase voltage transformer 2, and the controllable power supply is connected to the fault phase control module 103 It is electrically connected to the high-voltage switch 3 , the frequency sweep injection command sending module 104 is electrically connected to the controllable power supply 4 , and the real-time characteristic current receiving module 105 is connected to the fault indicator communication 501 . The communication connection method may preferably be a wireless communication method. The fault indicator 5 includes a characteristic current sending module, and the characteristic current sending module 501 is communicatively connected with the real-time characteristic current receiving module 105 . The working process of the centralized processor is: the three-phase bus-to-ground real-time voltage receiving module 101 receives the real-time three-phase-to-ground voltage sent by the three-phase voltage transformer 2, and the single-phase fault judgment module 102 judges according to the three-phase bus-to-ground voltage Whether there is a single-phase fault, if so, continue to judge the fault phase. When the faulty phase is judged, the controllable power source connected to the faulty phase control module 103 controls the high-voltage switch corresponding to the fault to close, so that the controllable power source is connected to the faulty phase. The frequency sweep injection command sending module 104 sends a fault point location command to the controllable power supply, so that it uses the frequency sweep method to inject a voltage or current with adjustable frequency and amplitude into the fault phase, and makes the fault point of the fault phase The characteristic current is generated on the line upstream of the The real-time characteristic current receiving module 105 receives the real-time characteristic current group sent by the fault indicator communication 501 in each fault indicator on the fault phase. The single-phase ground fault location module 106 determines that among the fault indicators corresponding to the three real-time characteristic current groups with unequal magnitudes of characteristic currents, the position behind the fault indicator farthest from the output end of the three-phase bus is the fault position. For the detailed process, please refer to the above-mentioned introduction about the three-stage working process of the distribution network single-phase-to-ground fault location system based on frequency-sweeping injection, which will not be repeated here.
需要说明的是，图1中的故障指示器是图3中的故障指示器中的几个，标记为A-E。在实际中,故障指示器的安装间距没有规定，可根据实际运行线路来定，通常，在故障易发线路中，每隔5km安放一个故障指示器。非故障易发线路，距离可以适当加大。为了发生单相接地故障后，巡线人员快速排除接地故障，方便巡线的区域可以稀疏安装，不方便巡线的区域需要密集安装。本发明定位单相接地故障点的地理准确度与电流检测器实际安装距离有关，安装越密集，地理定位信息越准确。It should be noted that the fault indicators in FIG. 1 are some of the fault indicators in FIG. 3 , which are marked as A-E. In practice, there is no regulation on the installation distance of the fault indicator, which can be determined according to the actual operating line. Usually, in the fault-prone line, a fault indicator is placed every 5km. For non-fault-prone lines, the distance can be appropriately increased. In order to quickly eliminate the ground fault after a single-phase ground fault occurs, the areas that are convenient for line inspection can be sparsely installed, and the areas that are not convenient for line inspection need to be densely installed. The geographical accuracy of the present invention to locate the single-phase grounding fault point is related to the actual installation distance of the current detector, the more intensive the installation, the more accurate the geographical positioning information.
综上所述，利用本发明提供的基于扫频注入的配电网单相接地故障定位方法，按照上述三个阶段的工作过程，应用在本发明提供的基于扫频注入的配电网单相接地故障定位系统中，能够提高三相中性点不接地系统配电网线路的单相接地故障的定位准确性。To sum up, using the single-phase ground fault location method of distribution network based on frequency sweep injection provided by the present invention, according to the working process of the above three stages, it is applied to the single-phase fault location method of distribution network based on sweep frequency injection provided by the present invention. In the ground fault location system, the positioning accuracy of the single-phase ground fault of the three-phase neutral point ungrounded system distribution network line can be improved.
以上所述仅是本发明的具体实施方式，应当指出，对于本技术领域的普通技术人员来说，在不脱离本发明原理的前提下，还可以做出若干改进和润饰，这些改进和润饰也应视为本发明的保护范围。The foregoing is only a specific embodiment of the present invention. It should be pointed out that for those of ordinary skill in the art, some improvements and modifications can also be made without departing from the principle of the present invention. It should be regarded as the protection scope of the present invention.
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711144938.0ACN107918079B (en) | 2017-11-17 | 2017-11-17 | Method and system for single-phase grounding fault location in distribution network based on sweep frequency injection |
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201711144938.0ACN107918079B (en) | 2017-11-17 | 2017-11-17 | Method and system for single-phase grounding fault location in distribution network based on sweep frequency injection |
| Publication Number | Publication Date |
|---|---|
| CN107918079Atrue CN107918079A (en) | 2018-04-17 |
| CN107918079B CN107918079B (en) | 2021-03-12 |
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201711144938.0AActiveCN107918079B (en) | 2017-11-17 | 2017-11-17 | Method and system for single-phase grounding fault location in distribution network based on sweep frequency injection |
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| CN (1) | CN107918079B (en) |
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